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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.drools.core.lock;
/**
* Lock held on a resource.
*/
public interface Lock {
/**
* Frees/release the lock.
*
* <p/>
* Note: client code may choose to invoke this method <i>before</i> the lock has been
* granted.
*
* @return {@code true} if the request was accepted, {@code false} if the lock is
* unavailable
*/
boolean free();
/**
* Determines if the lock is active.
*
* @return {@code true} if the lock is <b>ACTIVE</b>, {@code false} otherwise
*/
boolean isActive();
/**
* Determines if the lock is unavailable. Once a lock object becomes unavailable, it
* will never become active again.
*
* @return {@code true} if the lock is <b>UNAVAILABLE</b>, {@code false} otherwise
*/
boolean isUnavailable();
/**
* Determines if this object is waiting for a lock to be granted or denied. This
* applies when the lock is first created, or after {@link #extend(int, LockCallback)}
* has been invoked.
*
* @return {@code true} if the lock is <b>WAITING</b>, {@code false} otherwise
*/
boolean isWaiting();
/**
* Gets the ID of the resource to which the lock applies.
*
* @return the ID of the resource to which the lock applies
*/
String getResourceId();
/**
* Gets the lock's owner key.
*
* @return the lock's owner key
*/
String getOwnerKey();
/**
* Extends a lock an additional amount of time from now. The callback will always be
* invoked, and may be invoked <i>before</i> this method returns.
*
* @param holdSec the additional amount of time to hold the lock, in seconds
* @param callback callback to be invoked when the extension completes
*/
void extend(int holdSec, LockCallback callback);
}
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